THE BALLISTICS OF SORDARIA

Abstract

The structure of the perithecium of S. fimicola is redescribed. The horizontal distance of spore discharge is studied. Spores may be shot to a distance of up to 10.5 cm. The spore deposit from horizontal discharging perithecia contains spore groups (projectiles) of all possible sizes (i.e. with 1, 2, 3, 4, 5, 6, 7 or 8 spores). The more spores in a group the greater the mean distance of discharge. The existence of the different sizes of projectile in the deposit suggests that the spores tend to stick together, but separation may occur during discharge at any of the seven intervals in the row of eight escaping spores. On the assumption that a break is equally likely at any of these intervals, it is shown that the numbers of projectiles of the different sizes agree closely with expectation. The tendency of spores to stick together is greater at low than at high temperature. The mean distance of horizontal discharge of 8‐spore projectiles is about 20% higher at 21–24°C than at 7–10°C. Ascus jets discharging vertically have been analyzed by catching them on a rapidly rotating (c. 24 rev. per sec) horizontal disk of transparent ‘Perspex’. The results confirm the view that a break in the row of eight escaping spores can occur at any of the seven possible points of breakage. The initial velocity of the ascus jet is computed by two independent methods, both giving values of the same general order of magnitude. Copyright © 1959, Wiley Blackwell. All rights reserved